When Bill deVos gets a call about a dying or damaged tree, he doesn’t gear up for an execution; he packs his bag for a full-on forensic evaluation. The owner of Montpelier-based TreeWorks has an arsenal of tools to diagnose a tree’s weaknesses, and he’ll do anything he can to save one in trouble.
DeVos is part structural engineer and part arboreal artist. He and his team travel all over the country to evaluate projects, often rigging up complicated systems of triangulated cables and pulleys to support a tree’s weight. Sometimes, that means working in tight spots, such as a tiny courtyard behind a house at 78th and Madison Avenue in New York City, where a 60-foot willow threatened to come down on the neighbors. DeVos was also one of the experts consulted on how to save the famous 200-foot-tall California redwood dubbed Luna, in which activist Julia Butterfly Hill resided for two years.
But deVos usually can be found addressing the needs of trees here in Vermont. Seven Days caught up with him between projects.
SEVEN DAYS: You specialize in structural remediation of trees. Describe a typical house call.
BILL DEVOS: Every time I go to a tree call, it’s a forensic examination. We have to go back years to figure out what impacted a tree’s health. Sometimes it’s obvious … and sometimes we’ll sit under a tree and watch it sway in the wind for 45 minutes to see its weaknesses before starting to design a solution.
SD: What tools do you use to check a tree’s health?
BD: We often use sonic tomography, which is essentially a sonogram for trees that judges the density of the tree tissue. That gives us a basic “photograph” of the tree’s interior. Then I’ll use a resistograph to take an interior sample to give the exact dimensions of the decay. And sometimes you use a tree surgeon’s mallet to sound it out, along with a protractor and, of course, a computer.
SD: Can you tell just by looking at a tree if it’s healthy?
BD: A tree could essentially be dead and have a perfect set of leaves. Nobody pays attention to structural health — everyone looks at the outside. You might go to the nursery and pick out a tree with a perfect crown of leaves, but when I look inside, I see that, structurally, it’s going to destroy itself.
SD: So what do you do then?
BD: Most of the trees we’re called out to work on are so bad that we want to isolate the weakness and then distribute the energy over more mass so it doesn’t stress a particular area … We often use steel and fiberglass to rig up structural supports to distribute the weight.
SD: You were a full-time tree trimmer for 24 years; how did that influence your work as a tree preservationist?
BD: Yes, I started out as a climber (and still actively climb), but the job is much more than just trimming trees. You’re also an artist and a sculptor of negative space. It’s a challenging job — physically and also cognitively. You’re constantly challenged by the insects, diseases and myriad other problems that can hurt a tree. And it’s so important to do the right thing, because if you do something wrong today, it won’t show up for another five years.
SD: You’ve worked on some pretty interesting projects over the years; which ones stand out in your mind?
BD: I love figuring out solutions to interesting problems. We did a project for [Paul Newman’s nonprofit camp] Hole in the Wall Gang where we needed to cable 33 trees together to create a handicapped-accessible tree house that would sway in the wind as a unit. So we worked with a structural engineer to calculate how much the structures would move at certain wind speeds, and at different heights of the tree … We’re also in the middle of an ongoing project to transplant between 14,000 and 16,000 mature live oaks onto a golf course on Sea Island, Ga.
SD: Right now you’re planting, fertilizing and doing damage control for many local tree owners; what’s the biggest challenge Vermont trees face?
BD: People are the worst problem a tree could have. Soil compaction is another big reason for urban tree decline, and when a tree has compromised health, it’s more susceptible to long-term problems like disease and insects. Sugar maples always take a big hit here, too — everyone wants a maple in their backyard, but, in reality, you’d be much better off planting a red oak, or even a red maple, instead.
SD: Favorite aspect of your job?
BD: Arboriculture attracts people with short attention spans. You might use the same techniques, but you apply them in different ways every day. It never gets boring. And I love the structural remediation. Each project is totally unique, so you’re inventing remedies on the spot every time. It’s really rewarding when you revisit a project to see a tree standing years later that never would have lasted without help.
Work is a monthly interview feature showcasing a Vermonter with an interesting occupation. Suggest a job you would like to know more about: email@example.com.
The original print version of this article was headlined "The Tree Doctor Is In."